From your home screen, press the four squares button. A window will pop up at the bottom and you will see an icon for "settings". Press that, and the settings menu will appear. Scroll down to "applications". Press that, and the applications menu will appear. Press "quick launch", and the hot key list for your keyboard buttons will appear. Instead of tapping the key you want clear, press and hold it for a second, and a little window will pop up asking if you want to delete that button's setting. That's all there is too it